In blow molding machines of the wheel type, a wheel supports a plurality of circumferentially spaced sets of molds and is generally rotated about a horizontal axis. Plastic tubing is continuously extruded downwardly between the open mold sections and then the molds are closed as they move about an annular path and the portion of the tubing within the molds is blown within the confines of the mold to provide a hollow article which may be a container.
One of the limitations with such machines is that they are usually designed to handle a predetermined number of molds for making articles of a certain range of sizes. If smaller or larger articles are to be made, a different machine must be used. This, of course, requires a substantial investment in machines.
Accordingly, among the objectives of the present invention are to provide a blow molding machine that can be accommodate a variety of numbers of molds and mold sizes.
In accordance with the invention, the blow molding apparatus comprises a wheel plate, a shaft extending horizontally and supporting the wheel plate for rotation and a hub removably mounted on the shaft for rotation with the shaft, and a plurality of sets of molds defining a mold cavity when closed, each set comprising a pair of mold sections, a first mold section of each set being mounted on the hub such that the mold sections are circumferentially spaced about the hub, a second mold section of each set being mounted on the wheel in circumferentially spaced relation and radial alignment with the first mentioned mold section. The second mold sections are mounted on slide assemblies for movement toward and away from the first mold sections. The hub has circumferentially spaced external surfaces for supporting the first mold sections, the number of surfaces corresponding to the number of first mold sections. The hub may be removed and a second hub replaced on the shaft, having a plurality of circumferentially spaced surfaces, the number of the surfaces of the second hub differing from the number of surfaces of the first hub. The wheel plate accommodates a different number of slide assemblies to correspond with the different number of mold surfaces on the second hub.
In accordance with another aspect of the invention, the wheel plate accommodates mold mounting means in the form of slide assemblies that can be readily positioned, removed and adjusted circumferentially of the wheel plate.